Conventional battery charging systems, such as that disclosed in U.S. Pat. No. 4,320,335 to the present inventor, have employed a full wave bridge rectifier for connecting a single phase alternator winding to a battery to convert AC energy to DC energy to charge the battery. These systems require regulators to prevent overcharging of the battery by interrupting current flow to the battery when the battery voltage exceeds a predetermined value. Such regulators require components that can handle high current loads, particularly when the regulator is interrupting current flow. It is further desirable that such regulators be able to handle high energy transients that can occur, for example, when the battery is disconnected or has a loose connection, without damage to the regulator or other devices connected to the system.